Reduction of alcohol drinking in young adults by naltrexone: a double-blind, placebo-controlled, randomized clinical trial of efficacy and safety.

Objective: Naltrexone, an opioid antagonist, may facilitate reduction in drinking among young adults. We compared the efficacy and safety of naltrexone administered daily plus targeted dosing with placebo to reduce drinking in young adults who engage in heavy drinking.

Method: A randomized, double-blind, placebo-controlled study was conducted in an outpatient research center in March 2008-January 2012. Participants were aged 18-25 years and reported ≥ 4 heavy drinking days in the prior 4 weeks. Interventions included naltrexone 25 mg daily plus 25 mg targeted (at most daily) in anticipation of drinking (n = 61) or daily/targeted placebo (n = 67). All participants received a personalized feedback session and brief counseling every other week. Primary outcomes were percent heavy drinking days and percent days abstinent over the 8-week treatment period. Secondary outcomes included number of drinks per drinking day and percentage of days with estimated blood alcohol concentration (BAC) levels ≥ 0.08 g/dL.

Results: Of 140 randomized patients, 128 began treatment, comprising the evaluable sample. During treatment, percent heavy drinking days (naltrexone: mean = 21.60, SD = 16.05; placebo: mean = 22.90, SD = 13.20) (P = .58) and percent days abstinent (naltrexone: mean = 56.60, SD = 22.52; placebo: mean = 62.50, SD = 15.75) (P = .39) did not differ by group. Naltrexone significantly reduced the number of drinks per drinking day (naltrexone: mean = 4.90, SD = 2.28; placebo: mean = 5.90, SD = 2.51) (P = .009) and percentage of drinking days with estimated BAC ≥ 0.08 g/dL (naltrexone: mean = 35.4, SD = 28.40; placebo: mean = 45.7, SD = 26.80) (P = .042). There were no serious adverse events. Sleepiness was more common with naltrexone.

Conclusions: Naltrexone did not reduce frequency of drinking or heavy drinking days, but reduced secondary measures of drinking intensity. While effects were modest, the risk-benefit ratio favors offering naltrexone to help young adult heavy drinkers reduce the amount of alcohol they drink.

Trial Registration: ClinicalTrials.gov identifier: NCT00568958.